Plant biodiversity is threatened by habitat loss, fragmentation and invasion by exotic species, but the effects of these disturbances on individual plant species are rarely quantified. Since the 1950s, brigalow Acacia harpophylla forests in Australia have been extensively cleared and converted to pastures dominated by exotic grasses. Here we assess the habitat requirements, population numbers and threats for four poorly known bush tomato species, Solanum adenophorum, Solanum dissectum, Solanum elachophyllum and Solanum johnsonianum. Herbarium records and surveys demonstrated a strong association of all four species with brigalow habitat, although S. elachophyllum also occurred in other habitat. We derived historical and current population estimates from plant densities at current sites and the area of mapped brigalow habitat. Density estimates are imprecise because the survey data vary greatly, but the assessment indicates the populations of all four species have declined > 93%. Solanum dissectum and S. johnsonianum did not persist in cleared brigalow habitat, whereas S. adenophorum and S. elachophyllum had some capacity to persist in clearings. None of the species occur where the exotic grass cover is > 40%. Between 27% and 57% of the records of the four species are in brigalow remnants with a high edge-to-area ratio or open canopy (< 50% cover), making them highly vulnerable to invasive grasses. We recommend the categorization of S. dissectum and S. johnsonianum as Critically Endangered, S. adenophorum as Vulnerable and S. elachophyllum as Near Threatened.

Johann Wolfgang von Goethe, recognised as a seminal German polymath, developed a unique approach for investigating nature, termed “delicate empiricism”. Goethe's approach uses empathy, imagination and intuition to promote a participatory engagement with the world. It goes beyond the dualistic-rationalism that defines “conventional” ecological research and can lead to novel insights. “Delicate empiricism” was applied in an ecologically-degraded agricultural landscape in the Brigalow Belt, Queensland, Australia, and its potential for increasing landscape understanding and providing a basis for land-use design was assessed. It was found that Goethe's approach led to holistic, qualitative landscape awareness, not ordinarily accessible via “conventional science”. Application of “delicate empiricism” also gave rise to a land-use design that refected the Australian-ness of the Brigalow Belt landscape, particularly the potential for recovery of native biodiversity values through retention of regrowth vegetation. Overall, the study suggested that there is merit in educating Australian ecologists about “delicate empiricism” to encourage more creative and sensitive landscape management, that is in sync with the environment.